Report says warming altering N. America

An international panel of scientists says effects are already being seen.

By BILL ADAIR
Published April 17, 2007

WASHINGTON - A new study compiled by hundreds of scientists warns that Florida and other coastal states are especially vulnerable to the effects of global warming.

The study by the Intergovernmental Panel on Climate Change says there is growing evidence the warming is altering North America, disrupting ecosystems and threatening coastal states with rising sea levels and stronger hurricanes.

"Florida is particularly vulnerable because it's in hurricane alley," said Stephen Schneider, a climate scientist from Stanford University who contributed to the study. "We've already seen a substantial increase in the number of category 4 and 5 hurricanes."

He likened Florida's coastal development to a sand castle on the beach.

"You make it stronger and stronger so it doesn't wash away, yet the likelihood of it washing away goes up as the tide rises," Schneider said Monday at a Washington news conference. "But now we're not only increasing the level of the tide, we're increasing the intensity of the top-end storms" that could blow away the sand castle.

The IPCC report, compiled by more than 2,500 scientists from 130 countries, represents the international consensus about global warming.

The scientists reviewed hundreds of studies on topics ranging from sea level change to coastal erosion to butterfly migration. The authors say that the report is conservative and that the actual impacts are likely to be even more serious.

The group released an overview report in February that concluded it is highly likely that human activity is causing global warming. On Monday, the group released its findings on North America.

Michael Oppenheimer, a professor of geosciences at Princeton University, summarized the report by saying, "The more we learn, the more we find reasons to be concerned."

The draft report said global warming had already caused sweeping changes to species in North America. Although the greatest warming has been in Alaska and western Canada, all areas of the continent are feeling the impact.

The length of the vegetation growing season has increased an average of two days per decade since 1950, mostly from earlier warming in spring. Many plants are expanding their leaves or flowering earlier.

The warmer weather has altered the migration and breeding patterns of many species. Along the east coast of the United States, 28 bird species are nesting earlier. The Edith's Checkerspot butterfly, a species found in the Western portion of North America, is dying out in Mexico but found more in Canada.

Schneider said many other species, such as the Florida scrub jay, could be vulnerable to future habitat changes as other animals - and people - relocate because of the warmer climate.

Patricia Romero Lankao, a researcher at the National Center for Atmospheric Research, said the study shows an urgent need to reduce greenhouse gases.